Night-time ozone uptake by Mediterranean species

Abstract. Due to the evident tropospheric ozone impact on plant productivity, an accurate ozone risk assessment for the vegetation has become an issue. There is a growing evidence that ozone stomatal uptake may also take place at night and that the night-time uptake may be more damaging than diurnal uptake. Estimation of night-time uptake in the field is complicated because of instrumental difficulties. Eddy covariance technology is not always reliable because of the low turbulence at night. Leaf level porometry is defective at relative humidity above 70% which often takes place at night. Improved sap flow technology allows to estimate also slow flows that usually take place at night and hence may be, at present, the most trustworthy technology to measure night-time transpiration and hence to derive canopy stomatal conductance and ozone uptake at night. Based on micrometeorological data and the sap flow of three Mediterranean woody species, the night-time ozone uptake of these species was evaluated during a summer season as drought increased. Night-time ozone uptake was from 10% to 18% of the total daily uptake when plants were exposed to a weak drought, but increased up to 24% as the drought became more pronounced. The percentage increase is due to a stronger reduction of diurnal stomatal conductance than night-time stomatal conductance.

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Modelling bi-directional fluxes of methanol and acetaldehyde with the FORCAsT canopy exchange model

10.5194/acp-2016-522 ◽

2016 ◽

Author(s):

Kirsti Ashworth ◽

Serena H. Chung ◽

Karena A. McKinney ◽

Ying Liu ◽

Bill J. Munger ◽

...

Keyword(s):

Stomatal Conductance ◽

Atmospheric Chemistry ◽

Forest Canopy ◽

Global Scale ◽

Exchange Model ◽

Forest Site ◽

Canopy Exchange ◽

Harvard Forest ◽

Leaf Level ◽

Underlying Mechanisms

Abstract. The FORCAsT canopy exchange model was used to investigate the underlying mechanisms governing foliage emissions of methanol and acetaldehyde, two short chain oxygenated volatile organic compounds ubiquitous in the troposphere and known to have strong biogenic sources, at a northern mid-latitude forest site. The explicit representation of the vegetation canopy within the model allowed us to test the hypothesis that stomatal conductance regulates emissions of these compounds to an extent that its influence is observable at the ecosystem-scale, a process not currently considered in regional or global scale atmospheric chemistry models. We found that FORCAsT could only reproduce the magnitude and diurnal profiles of methanol and acetaldehyde fluxes measured at the top of the forest canopy at Harvard Forest if light-dependent emissions were introduced to the model. With the inclusion of such emissions FORCAsT was able to successfully simulate the observed bi-directional exchange of methanol and acetaldehyde. Although we found evidence that stomatal conductance influences methanol fluxes and concentrations at scales beyond the leaf-level, particularly at dawn and dusk, we were able to adequately capture ecosystem exchange without the addition of stomatal control to the standard parameterisations of foliage emissions, suggesting that ecosystem fluxes can be well enough represented by the emissions models currently used.

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Coupled carbon-water exchange of the Amazon rain forest, I. Model description, parameterization and sensitivity analysis

Biogeosciences Discussions ◽

10.5194/bgd-2-333-2005 ◽

2005 ◽

Vol 2 (2) ◽

pp. 333-397 ◽

Cited By ~ 2

Author(s):

E. Simon ◽

F. X. Meixner ◽

L. Ganzeveld ◽

J. Kesselmeier

Keyword(s):

Stomatal Conductance ◽

Leaf Area ◽

Rain Forest ◽

Canopy Structure ◽

Leaf Nitrogen ◽

Optical Parameters ◽

Amazon Rain Forest ◽

Leaf Level ◽

Net Assimilation ◽

Parameter Values

Abstract. Detailed one-dimensional multilayer biosphere-atmosphere models, also referred to as CANVEG models, are used for more than a decade to describe coupled water-carbon exchange between the terrestrial vegetation and the lower atmosphere. Within the present study, a modified CANVEG scheme is described. A generic parameterization and characterization of biophysical properties of Amazon rain forest canopies is inferred using available field measurements of canopy structure, in-canopy profiles of horizontal wind speed and radiation, canopy albedo, soil heat flux and soil respiration, photosynthetic capacity and leaf nitrogen as well as leaf level enclosure measurements made on sunlit and shaded branches of several Amazonian tree species during the wet and dry season. The sensitivity of calculated canopy energy and CO2 fluxes to the uncertainty of individual parameter values is assessed. In the companion paper, the predicted seasonal exchange of energy, CO2, ozone and isoprene is compared to observations. A bi-modal distribution of leaf area density with a total leaf area index of 6 is inferred from several observations in Amazonia. Predicted light attenuation within the canopy agrees reasonably well with observations made at different field sites. A comparison of predicted and observed canopy albedo shows a high model sensitivity to the leaf optical parameters for near-infrared short-wave radiation (NIR). The predictions agree much better with observations when the leaf reflectance and transmission coefficients for NIR are reduced by 25–40%. Available vertical distributions of photosynthetic capacity and leaf nitrogen concentration suggest a low but significant light acclimation of the rain forest canopy that scales nearly linearly with accumulated leaf area. Evaluation of the biochemical leaf model, using the enclosure measurements, showed that recommended parameter values describing the photosynthetic light response, have to be optimized. Otherwise, predicted net assimilation is overestimated by 30–50%. Two stomatal models have been tested, which apply a well established semi-empirical relationship between stomatal conductance and net assimilation. Both models differ in the way they describe the influence of humidity on stomatal response. However, they show a very similar performance within the range of observed environmental conditions. The agreement between predicted and observed stomatal conductance rates is reasonable. In general, the leaf level data suggests seasonal physiological changes, which can be reproduced reasonably well by assuming increased stomatal conductance rates during the wet season, and decreased assimilation rates during the dry season. The sensitivity of the predicted canopy fluxes of energy and CO2 to the parameterization of canopy structure, the leaf optical parameters, and the scaling of photosynthetic parameters is relatively low (1–12%), with respect to parameter uncertainty. In contrast, modifying leaf model parameters within their uncertainty range results in much larger changes of the predicted canopy net fluxes (5–35%).

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Sap flow, leaf-level gas exchange and spectral responses to drought in Pinus sylvestris, Pinus pinea and Pinus halepensis

iForest - Biogeosciences and Forestry ◽

10.3832/ifor1748-009 ◽

2017 ◽

Vol 10 (1) ◽

pp. 204-214 ◽

Cited By ~ 4

Author(s):

JA Manzanera ◽

A Gómez-Garay ◽

B Pintos ◽

M Rodríguez-Rastrero ◽

E Moreda ◽

...

Keyword(s):

Gas Exchange ◽

Pinus Sylvestris ◽

Sap Flow ◽

Pinus Halepensis ◽

Pinus Pinea ◽

Leaf Level ◽

Spectral Responses

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Growth and grain yield of eight maize hybrids is aligned with water transport, stomatal conductance, and photosynthesis in a semi-arid irrigated system

10.1101/2021.02.04.429760 ◽

2021 ◽

Author(s):

Sean M Gleason ◽

Lauren Nalezny ◽

Cameron Hunter ◽

Robert Bensen ◽

Satya Chintamanani ◽

...

Keyword(s):

Stomatal Conductance ◽

Grain Yield ◽

Water Transport ◽

Co2 Assimilation ◽

Specific Conductance ◽

Soil Conditions ◽

Transport Pathway ◽

Crop Species ◽

Leaf Level ◽

Improved Performance

There is increasing interest in understanding how trait networks can be manipulated to improve the performance of crop species. Working towards this goal, we have identified key traits linking the acquisition of water, the transport of water to the sites of evaporation and photosynthesis, stomatal conductance, and growth across eight maize hybrid lines grown under well-watered and water-limiting conditions in Northern Colorado. Under well-watered conditions, well-performing hybrids exhibited high leaf-specific conductance, low operating water potentials, high rates of midday stomatal conductance, high rates of net CO2 assimilation, greater leaf osmotic adjustment, and higher end-of-season growth and grain yield. This trait network was similar under water-limited conditions with the notable exception that linkages between water transport, midday stomatal conductance, and growth were even stronger than under fully-watered conditions. The results of this experiment suggest that similar trait networks might confer improved performance under contrasting climate and soil conditions, and that efforts to improve the performance of crop species could possibly benefit by considering the water transport pathway within leaves, as well as within the whole-xylem, in addition to root-level and leaf-level traits.

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Ozone uptake by adult urban trees based on sap flow measurement

Environmental Pollution ◽

10.1016/j.envpol.2011.11.026 ◽

2012 ◽

Vol 162 ◽

pp. 275-286 ◽

Cited By ~ 17

Author(s):

Hua Wang ◽

Weiqi Zhou ◽

Xiaoke Wang ◽

Fuyuan Gao ◽

Hua Zheng ◽

...

Keyword(s):

Sap Flow ◽

Flow Measurement ◽

Urban Trees ◽

Ozone Uptake

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Simulation of stomatal conductance for Aleppo pine to estimate its ozone uptake

Environmental Pollution ◽

10.1016/j.envpol.2006.08.008 ◽

2007 ◽

Vol 146 (3) ◽

pp. 617-623 ◽

Cited By ~ 19

Author(s):

Susana Elvira ◽

Rocío Alonso ◽

Benjamín S. Gimeno

Keyword(s):

Stomatal Conductance ◽

Aleppo Pine ◽

Ozone Uptake

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Coupled carbon-water exchange of the Amazon rain forest, I. Model description, parameterization and sensitivity analysis

Biogeosciences ◽

10.5194/bg-2-231-2005 ◽

2005 ◽

Vol 2 (3) ◽

pp. 231-253 ◽

Cited By ~ 7

Author(s):

E. Simon ◽

F. X. Meixner ◽

L. Ganzeveld ◽

J. Kesselmeier

Keyword(s):

Stomatal Conductance ◽

Leaf Area ◽

Rain Forest ◽

Canopy Structure ◽

Leaf Nitrogen ◽

Optical Parameters ◽

Amazon Rain Forest ◽

Leaf Level ◽

Net Assimilation ◽

Parameter Values

Abstract. Detailed one-dimensional multilayer biosphere-atmosphere models, also referred to as CANVEG models, are used for more than a decade to describe coupled water-carbon exchange between the terrestrial vegetation and the lower atmosphere. Within the present study, a modified CANVEG scheme is described. A generic parameterization and characterization of biophysical properties of Amazon rain forest canopies is inferred using available field measurements of canopy structure, in-canopy profiles of horizontal wind speed and radiation, canopy albedo, soil heat flux and soil respiration, photosynthetic capacity and leaf nitrogen as well as leaf level enclosure measurements made on sunlit and shaded branches of several Amazonian tree species during the wet and dry season. The sensitivity of calculated canopy energy and CO2 fluxes to the uncertainty of individual parameter values is assessed. In the companion paper, the predicted seasonal exchange of energy, CO2, ozone and isoprene is compared to observations. A bi-modal distribution of leaf area density with a total leaf area index of 6 is inferred from several observations in Amazonia. Predicted light attenuation within the canopy agrees reasonably well with observations made at different field sites. A comparison of predicted and observed canopy albedo shows a high model sensitivity to the leaf optical parameters for near-infrared short-wave radiation (NIR). The predictions agree much better with observations when the leaf reflectance and transmission coefficients for NIR are reduced by 25–40%. Available vertical distributions of photosynthetic capacity and leaf nitrogen concentration suggest a low but significant light acclimation of the rain forest canopy that scales nearly linearly with accumulated leaf area. Evaluation of the biochemical leaf model, using the enclosure measurements, showed that recommended parameter values describing the photosynthetic light response, have to be optimized. Otherwise, predicted net assimilation is overestimated by 30–50%. Two stomatal models have been tested, which apply a well established semi-empirical relationship between stomatal conductance and net assimilation. Both models differ in the way they describe the influence of humidity on stomatal response. However, they show a very similar performance within the range of observed environmental conditions. The agreement between predicted and observed stomatal conductance rates is reasonable. In general, the leaf level data suggests seasonal physiological changes, which can be reproduced reasonably well by assuming increased stomatal conductance rates during the wet season, and decreased assimilation rates during the dry season. The sensitivity of the predicted canopy fluxes of energy and CO2 to the parameterization of canopy structure, the leaf optical parameters, and the scaling of photosynthetic parameters is relatively low (1–12%), with respect to parameter uncertainty. In contrast, modifying leaf model parameters within their uncertainty range results in much larger changes of the predicted canopy net fluxes (5–35%).

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Water and Soil Nutrient Dynamics of Huanglongbing-Affected Citrus Trees as Impacted by Ground-Applied Nutrients

Agronomy ◽

10.3390/agronomy10101485 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1485 ◽

Cited By ~ 1

Author(s):

Alisheikh A. Atta ◽

Kelly T. Morgan ◽

Said A. Hamido ◽

Davie M. Kadyampakeni ◽

Kamal A. Mahmoud

Keyword(s):

Leaf Area ◽

Sap Flow ◽

Untreated Control ◽

Soil Nutrient ◽

Irrigation Scheduling ◽

Summer Season ◽

Stem Water Potential ◽

Area Index ◽

Available N ◽

Citrus Trees

The decrease in the rate of inflow and outflow of water—and thereby the uptake of plant nutrients as the result of Huanglongbing (HLB or citrus greening)—leads to a decline in overall tree growth and the development of nutrient deficiencies in HLB-affected citrus trees. This study was conducted at the University of Florida, Southwest Florida Research and Education Center (SWFREC) near Immokalee, FL from January 2017 through December 2019. The objective of the study was to determine the effect of rootstocks, nutrient type, rate, and frequency of applications on leaf area index (LAI), water relations (stomatal conductance [gs], stem water potential [Ψw], and sap flow), soil nutrient accumulation, and dynamics under HLB-affected citrus trees. The experiment was arranged in a split-split plot design that consisted of two types of rootstocks, three nitrogen (N) rates, three soil-applied secondary macronutrients, and an untreated control replicated four times. LAI significantly increased in response to the secondary macronutrients compared with uncontrolled trees. A significantly greater gs, and thus a decline in Ψw, was a manifestation of higher sap flow per unit LA (leaf area) and moisture stress for trees budded on Swingle (Swc) than Cleopatra (Cleo) rootstocks, respectively. The hourly sap flow showed significantly less water consumption per unit LA for trees that received a full dose of Ca or Mg nutrition than Ca + Mg treated and untreated control trees. The soil nutrient concentrations were consistently higher in the topmost soil depth (0–15 cm) than the two lower soil depths (15–30 cm, 30–45 cm). Mobile nutrients: soil nitrate–nitrogen (NO3-N) and Mg2+ Mg2+, Mn2+, Zn2+, and B leached to the lower soil (15–30 cm) depth during the summer season. However, the multiple split applications of N as Best Management Practices (BMPs) and optimum irrigation scheduling based on reference evapotranspiration (ETo) maintained soil available N (ammonium nitrogen [NH4-N] and NO3-N) below 4.0 mg kg−1, which was a magnitude 2.0–4.0× less than the conventional N applications. Soil NH4-N and NO3-N leached to the two lower soil depths during the rainy summer season only when trees received the highest N rate (280 kg ha−1), suggesting a lower citrus N requirement. Therefore, 224 kg ha−1 N coupled with a full Ca or Mg dose could be the recommended rate for HLB-affected citrus trees.

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